# Physics

posted by Joordan

A proton is fired with a speed of 3.00 X 10^6 m/s directly towards a large and positively charged plane of surface charge density +9.25 X 10^-7 C/m^2 . If the proton starts 1m from the plane, the minimum distance between the proton and the plane is closest to.. ?
A) 0cm B) 10cm C) 45cm D) 55cm E) 90cm

I know the answer is B, but not quite sure why :S

Any help would be appreciated, thank you.

1. drwls

Use the surface charge density to compute the E field perpendicular to the plate. The field will be independent of distance from the plate, if the plate is large compared to the distance from the plate.

E = (charge density)/(epsilon-zero)

Minimum distance occurs when the work done by the proton against the field the field equals the initial kinetic energy.

Be sure to subtract the distabnce travelled from 1 meter to get the distance from the wall at turnaround.

## Similar Questions

1. ### Physics

A proton orbits a negatively charged wire that has a linear charge density of 8.0 x 10 -9 C/m. What speed must the proton have to maintain a circular orbit at 1.3 cm?
2. ### Physics

Nuclear fusion reactions require that positively charged nuclei be brought into close proximity, against the electrostatic repulsion. As a simple example, suppose a proton is fired at a second, stationary proton from a large distance …
3. ### Physics

Nuclear fusion reactions require that positively charged nuclei be brought into close proximity, against the electrostatic repulsion. As a simple example, suppose a proton is fired at a second, stationary proton from a large distance …
4. ### Physics

Nuclear fusion reactions require that positively charged nuclei be brought into close proximity, against the electrostatic repulsion. As a simple example, suppose a proton is fired at a second, stationary proton from a large distance …
5. ### Physics

Nuclear fusion reactions require that positively charged nuclei be brought into close proximity, against the electrostatic repulsion. As a simple example, suppose a proton is fired at a second, stationary proton from a large distance …
6. ### Physics

A proton moves eastward in the plane of Earth’s magnetic equator so that its distance from the ground remains constant. What is the speed of the proton if Earth’s magnetic field points north and has a magnitude of 5.2 × 10−5 …
7. ### Physics

A proton moves eastward in the plane of Earth’s magnetic equator so that its distance from the ground remains constant. What is the speed of the proton if Earth’s magnetic ﬁeld points north and has a magnitude of 5.2 × …
8. ### Physics

Nuclear fusion reactions require that positively charged nuclei be brought into close proximity, against the electrostatic repulsion. As a simple example, suppose a proton is fired at a second, stationary proton from a large distance …
9. ### physics

A large plane having uniform charge density has an electric field just outside the plane that points directly toward the plane with magnitude 1.25×104N/C . What is the surface charge density?
10. ### Physics

A proton is fired from far away toward the nucleus of a mercury atom. Mercury is element number 80, and the diameter of the nucleus is 14.0 fm. The proton is fired at a speed of 1.80×107 m/s. When it passes the nucleus, how close …

More Similar Questions